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IMAX 2000 VERSES THE SOLARCON / ANTRON 99

I know this has been talked about before and with new members here maybe we have more answers or info. I want to know or hear about any differences between the Imax 2000 and the Antron 99 I am asking because I have always and currently have a Solarcon 99 up for 10-17 meters and also have a Imax 2000 in the pile or collection of antennas and was thinking about if it would be worth taking the Antron 99 with Groundplane kit down and putting the Imax up in its place and if I should buy the groundplane kit adon for the Imax aswell.

Is there a big noticeable difference in the performance between these 2 antennas??? Ive always had good luck with the Antron 99 and have not one single complaint but if this Imax 2000 is better and worth swapping with the Antron Ide do it tomorrow. What are your thoughts and or experiences with these antennas compared to eachother??? Ive heard people say that locally the Imax was better and as far as skip or DX the Antron was better I imagine if this was true it would be due to the take off angle between the 2 antennas but it still does not seem that there could be such a dramatic difference between the 2 antennas as far as local or close talking.

What is the truth here what are the differences are they really that noticeable?? I figured since I have an Imax here if its worth putting up I will do just that but if its not worth doing then what is the sense?? Also what about the groundplane kit?? Ive been told The kit for the Antron 99 is a waste of money and makes no difference I wouldnt know because Ive always ran the kit on my Antron 99 antennas. Thanks for any input and info on this mystery.....Tony

Last year I replaced a slightly damaged A99 (cracked f'glass) with a used Imax. Locally I picked up "about" 1/2 S unit or so, according to a reliable source. Exact same mounting scheme, same coax, etc. FWIW.

I don't know about DX performance, I use my directional arrays for that. Just my $.02.

Tony, these are signal reports I took last summer comparing some of my antennas. I compare two at a time using a switch box and I'll grant you this is not even close to scientific. They were taken over a 1-3 day periods in some cases and less than one day in others. I'm too old to go rushing around trying to change antennas and test on the same setup. Plus I get the advantage of comparing differences in the flip of a switch, and if you have never done that, then you just miss out on some, maybe all of the scuttle differences that can be noted between different antennas at times.

the 2000 is a better constructed antenna and most folks that have had both say the bigger imax is better . comments on adding the ground plane kit vary from no effect to big difference . both the 99 and 2000 will use your mast/coax shield for a ground plane if you dont add one . some folks that had splatter issues and bleeding into nearby electronics without the GPK said the were reduced or eliminated by add the GPK . a coax choke 9 feet down the coax from the antennas feed point is a good idea .

T225,
Tony,
I use a A99 after doing direct testing of both antennas at 5-10-15-20 & 25 miles to a mobile on both T & R on 11 meters. I tested an IMAX an a A99 on 10-12 -15 -17 & 20 meters an got a shade better SWR with the IMAX over a A99 for HAM needs eather antenna is a lot of bang for the buck..........Oldtimer

T225,
Tony,
I use a A99 after doing direct testing of both antennas at 5-10-15-20 & 25 miles to a mobile on both T & R on 11 meters. I tested an IMAX an a A99 on 10-12 -15 -17 & 20 meters an got a shade better SWR with the IMAX over a A99 for HAM needs eather antenna is a lot of bang for the buck..........Oldtimer

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Again I have to agree with Walterb, I've seen very similar results with these two antennas at my location. I have added the GPK, both horizontal and slanted, to the A99, with little noticeable difference. I don't have a GPK for my Imax. I also never used these antennas for anything except 11 meters.

I just posted in another thread, my comparison results between my A99, and my I-10K, and I'll post it again here just as a reference. Like the I-10K, my Imax was not up very long, and I only have one signal report (#25) for it.

Marconi,
I tried adding ground plane to both the A99 and the IMAX, a slight SWR change was noticed on 11 meters, more on other bands but that is understandable.
I did not detected changes against a reference antenna on R or T
on the A99 on 11 meters, do think the noise floor changed a little on the IMAX but I can't prove it ether, I had read that another person thought that he thought it did. Could have preprogramed myself to hear something like that................Oldtimer

Marconi,
I tried adding ground plane to both the A99 and the IMAX, a slight SWR change was noticed on 11 meters, more on other bands but that is understandable.
I did not detected changes against a reference antenna on R or T
on the A99 on 11 meters, do think the noise floor changed a little on the IMAX but I can't prove it ether, I had read that another person thought that he thought it did. Could have preprogramed myself to hear something like that................Oldtimer

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Walter, the only difference that I could detect by adding the GPK to the A99, was the bandwidth narrowed a bit, and instead of an almost flat bandwidth curve there developed a nice bowl shaped curve instead. There are comments among my reports and antenna notes about noise, but I have not studied them yet...to see if there are any conclusions to be made. These comments could have just been about the noise conditions for the day...and nothing more.

Marconi,
I had a R/S .64 Crossbow antenna in service from 1990 to 2002 when I lived in LV, NV talked and could hear a strong station at the state line 60+ miles away on a Cobra 2000GTL. Talk to my wife when coming back from LA to LV on inter state 15, 15 miles in to Ca on SSB, but did have some elevation when still in Ca. Think the .64 an the HGP-500 were in the same league, big problem with the R/S .64 was the matching network in the base, would only take about 200 watts max. Had more FUN with the .64 I got 3 of them from R/S for $9.00 each back were they were closing them out, wish I had it today as a reference antenna..............Oldtimer

The primary difference between those two antennas are their radiation patterns. The Imaxx, a 5/8 wave antenna, tends to have a lower 'start' to it's radiation pattern than the 'A99', a 1/2 wave antenna. The Imaxx's pattern is 'flatter'. And then you get into how things around any antenna tends to affect it's radiation pattern. There will always be some affect, and there's not really any reliable way of predicting exactly what will happen, what will change and how. The antenna modeling programs can certainly give an indication of what happens, but it isn't going to be very reliable unless you do one hell of a lot of modeling of those 'things' around the antenna that will affect things. And then the result will ONLY be valid for the one set of circumstances that you modeled. Move that antenna 10 feet in one direction or another and you get to start all over again from scratch. Oooo Yeah, that sounds exciting, doesn't it! (Yeah, right.)
So it comes down to trying it and see what happens.
- 'Doc

The primary difference between those two antennas are their radiation patterns. The Imaxx, a 5/8 wave antenna, tends to have a lower 'start' to it's radiation pattern than the 'A99', a 1/2 wave antenna. The Imaxx's pattern is 'flatter'.

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I agree with Doc' that the patterns for the Imax vs. A99 are different, but I don't see a difference like Doc' describes...lower for the Imax.

Here are my Eznec models for these two at 40' feet high to the feed point with a 39.5' foot isolated (ISO) mast for each.

Note: the Imax is the overlay pattern here and shows max gain of 3.68 at 8* degrees vs. the *Primary pattern for the A99 at the same 8* degrees, but look at all the energy pushed up high for the 5/8 wave.

And then you get into how things around any antenna tends to affect it's radiation pattern. There will always be some affect, and there's not really any reliable way of predicting exactly what will happen, what will change and how. The antenna modeling programs can certainly give an indication of what happens, but it isn't going to be very reliable unless you do one hell of a lot of modeling of those 'things' around the antenna that will affect things. And then the result will ONLY be valid for the one set of circumstances that you modeled. Move that antenna 10 feet in one direction or another and you get to start all over again from scratch. Oooo Yeah, that sounds exciting, doesn't it! (Yeah, right.)
So it comes down to trying it and see what happens.
- 'Doc

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I've been trying to model an antenna farm idea that Doc's suggested here, but it is a very complicated model for me. Here is the start without results. I note one thing for sure, there is interference to be noted even at 36' feet apart. I'm not sure yet if it is always destructive interference however or if all antennas are affected the same.

At first I was just going to model my Gain Master, as active, just like it is mounted here and simulate the Starduster and A99 sitting on masts at the same height at my other mounts. In the process of modeling, I decided instead to make three models of the same thing, and then make a model for each as an active antenna with a source. This required me to make the simulated models more to scale, and that complicated the idea.

All antennas are mounted at 20' feet to the feed point. There are no details yet, but the GM, in this case, is the active (radiating model) with a power source. I still have to model the Starduster to scale, and then I can make a model with it as the active model. The GM and the A99 are easy to set to scale, model, and add a source for.

Here is my start-up model for the antenna farm at my location, including a GM standing alone to be used as a comparison.

You know, Marconi, all that 'stuff' around an antenna doesn't necessarily mean other antennas.
- 'Doc

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Well guys, 'Doc may wish for me to model the entire Harris County Metroplex in order to cover all contingencies for what happens to antennas with stuff nearby, but that is not going to happen. Just modeling these three antennas in an antenna farm at 36', 72', and 108' feet apart...is quite revealing. I would try and demonstrate this, as usual, with more PDF files of my model, but for two issues.

1. 'Doc is absolutely right about antennas being affected by stuff on the Earth. In my model here, it is evident even out to 108' feet with just two antennas side by side. I removed the A99 from the main model for this part of the project. With the GM as the source antenna, the SD'r at any distance in the range from 36' - 108' feet...the GM pattern was affected just like 'Doc says. There might not be as much of an affect, in all aspects as 'Doc and other's suspect, but it did surprised me none the less. I was thinking that maybe 36' feet apart might be enough to kill most interaction. There are many possible variables even with only two antennas in the model, much less three.

2. I would post the models and try and explain what I think, but I'm not sure yet that I understand the resulting directional relationship of the Antenna View to the pattern view in the 3-dimensional display in free space. The free space models may be the only way to look at 'Doc's idea. It would be nice to be able to do this over real Earth, but I think Eznec only allows us to do the 3 dimensional view with the source model in free space, with no losses, and no connection to the Earth. In these real world Eznec models, I have all antenna masts attached to the earth. I haven't figured out the resulting directional factors for the free space models yet, and that difference that 'Doc mentions, is a skewing affect on the pattern. That affect allows the model to sill be omni-directional, but with modest gain differences at different compass headings.

All I can see here is that when two antennas are mounted close together, the affects are so complicated that my lack of understanding and trying to explain...would be almost futile.

Again, remember that I asked 'Doc how much difference stuff around an antenna really made. Again, I don't see that much change in the gain or the maximum angle of radiation...for these antennas mounted alone vs. the antenna farm, but there is certainly skewing to be noted in the free space patterns if I were to go there. And, when I remove the passive antennas from the antenna view, the skewed free space pattern returns to fully omni-directional...just as we might expect.

I did not model these in free space, but I did go there to get Average Gain values for the models, and check if I could see more of a difference in the patterns. I think I did see more of a pattern difference using free space models. The Eznec real Earth models here hardly changed at all. So, maybe 'Doc was referring to free space affects, as making the big difference. Most "professional" RF guys tend to talk in terms of antenna efficiency and free space ideas...when they write or talk. For me, that must be considered in your understanding for whatever you read or hear said.

I conclude that my models, over real Earth, are not that far off from what I might be seeing here...with real antennas at my location. As a note, I also did not mess with changing the Earth conditions for these models, and modeled over Average Earth. I also tried to keep all wire segment lengths at near 1' foot.

Regarding my descriptors for my model entitled: "Gain Master' SD A99 ISO 19.5'.ez". The (') following (Gain Master') simply means the GM is the source antenna for this model. If there is an "ISO" noted after the antenna's descriptions, it means the antenna has a 6" isolator at the antenna end of the mast...with the bottom end attached at the Earth. The (') was likewise used for the SD'r and the A99 when they were made active with a power source for this idea. As a note: in the Antenna View, the source antenna has the red circle at the feed point and is the radiating antenna.

One of the most remarkable things I noticed here, was when I isolated (ISO) the A99 from its mast. It is obvious in the three attached Antenna Views that the current flow, noted in red, originates from the GM. However, I ask that you note the considerably increased passive current flows on the A99 that is isolated vs. those on the A99 that is not isolated. I conclude that this quirk does not seem to disagree with what science might predicts, and that antenna construction and passive resonance on conductive elements...is also of much importance for 'Doc's issue.

It was my thought that this happened due to the isolation of the 1/2 wave portion for the A99, and thus provided for the 1/2 wave to just be sitting out there in free space, so-to-speak. Conversely, when the mast was not isolated, the A99 looked like a wavelength or longer element with the mast attached. Thus it did not respond as well to the RF radiating from the GM...kind of like a proper reflector should do on a yagi multi-element beam. I was surprised to see Eznec indicate this, but again I think this is probably what science would predict. However, this was all very interesting to see happen in the model...even if the models are not right-on-the-mark.

I might have some more to say about this idea, but I don't see how I could really explain all the issues these models present. IMO, you guys would probably need to understand something about modeling, and then be able to manipulate the files yourself and see what is happening.

Else I'd would post some more of these Eznec examples showing how similar the patterns are and with the exception noted above...just how little difference there is at one wavelength in spacing between antennas.

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